Ammunition



Jan. 5, 1960 .1. DEAR mm 2 9 AMMUNITION Filed May 25. 1953 COATING: 8 ONI ICD. l

INVENTORS JOHN C. DEAR BY ROBERT e. owzws RONALD A. GULLEY ATTORNEYS;

AMlVIUNITION John C. Dear, East Alton, and Robert G. Owens, Wood River,111., and Ronald A. Gulley, Jenn ngs, Mo., assignors to Olin MathiesonChemical (Jot-partition, a corporation of Virginia Application May 25,1953, Serial No. 357,391

9 Claims. ((11. 102-'42) This invention relates generally to ammunitionand more particularly to a novel shot shell having improved ballisticcharacteristics.

At one time, shot shell cases were extensively made of brass but, inorder to compensate for the cost thereof, most consumers were forced toreload the case as many times as the case would permit. As a result, assoon as a procedure was developed for making an expendable shot shellcase from a paper tube and a brass head, manufacture of the brass shellcase was almost entirely discontinued in favor of the newer development.The paper shot shell case has been found eminently suitable for mostpurposes but it has been found that it does not always function properlyafter exposure to humid weather conditions or when it is fired attemperatures of 32 F. or lower. Because of these dificiencies of thepaper shell, there has been a constant endeavor to develop an expendableshot shell case which is not deleteriously affected by inclement Weatherbut none of the substitutes heretofore proposed, including steel shotshell cases, have been sufiiciently advantageous to replace the papershot shell in practice. Although aluminum rifle cartridge cases havebeen proposed in the art, attempts to make shot shells having analuminum case have been unsuccessful for various reasons. One of themost disconcerting problems encountered in making a suitable aluminumshot shell has been to obtain satisfactory ballistic characteristics.Heretofore, shot shells having an aluminum case and loaded with apowdersuitable for imparting the proper velocity to the shot have almostwithout an exception produced dangerously high pressures when the shellwas fired.

It is therefore an object of this invention to provide a novel andexpendable shot shell case. It is another object of this invention toprovide a shot shell having an expendable case which will functionproperly in a shotgun in inclement weather. Another object of theinvention is to provide a shot shell having an aluminum case and havingsatisfactory ballistic properties. More speecifically, it is an objectof this invention to provide a shot shell having an aluminum case whichcan be loaded to have ballistic properties equivalent to the paper shotshell under all weather conditions and which will also functionsatisfactorily in a shotgun under inclement weather conditions. Anotherobject is to provide a method for improving the ballistic performance ofaluminum shot shells.

The foregoing objects as well as others are achieved in accordance withthis invention by providing a shot shell having an aluminum caseseparated from the metallic shot contained therein by a layer of anon-metallic material. lt has been found that a shot shell having analuminum case containing a powder suitable for paper shells can beloaded to the required shot velocity without hazardous pressures beingdeveloped when the shell is fired provided contact between the innerwall of the shell case and the metallic shot is prevented by anintervening layer of a non-metallic material.

Additional objects and advantages will be apparent from the followingdescription and drawings in which:

Figure 1 is a schematic partial sectional view ,of an embodiment of theinvention showing a shot shell with a coating applied to the inner wallof the shell case;

Figure 2 is a schematic partial sectional view of another embodiment ofthe invention showing an aluminum shot shell with a coating applied tothe shot pellets.

Referring to the drawings this invention contemplates a shot shellprovided with an aluminum shell case 1 having a hollow 2 defined by saidwalls 3. The hollow 2 contains shot pellets 4, and an over powder wad 5separating the shot pellets 4 from a powder charge 6. The shot pellets 4are held in the hollow 2 by a top wad 7. Any suitable primer may beprovided for igniting the powder 6. The aluminum shot shell is providedwith a substantially continuous and adherent non-metallic coating 8 onthe surface of either the shot 4, as illustrated in Figure 2, or theinner wall 3 of the shot shell case 1, as illustrated in Figure 1, orboth. Any non-metallic material which can be applied to either the shot4 or the inner wall 3 of the shell case l in the form of a substantiallycontinuous film 8 and which will not otherwise interfere with theperformance of the shot shell can be utilized. For example, non-metallicfilms of natural occurring resins such as ester gum and the like, filmsof synthetic resins such as ethyl cellulose, phenol formaldehyde,polystyrene, polyesters, epoxy and the like, films of a lacquer such asa nitrocellulose lacquer and films of a wax such as paraffin wax,microcrystalline wax, carnauba wax, ceresin wax and the like have beenfound admirably suited for the purpose. The resins and waxes can usuallybest be applied in the form of a solution thereof by dipping, spraying,or other conventional coating process. For best results the meltingpoints of the coating should be above about 120 F. In a preferred formof the invention illustrated in Figure 1 the shot and inner wall of thecase are separated by a layer of aluminum oxide adhering to the innerwall of the case. Coatings of other aluminum compounds such as aluminumfluoride, for example, are also suitable for the purpose. Only thatportion of the inner wall 3 of the aluminum shot shell case 1 adjacentthe shot 4 charge need be coated but no special precautions need betaken to prevent the entire inner wall from becoming coated. Thethickness of coating 8 required is not necessarily critical although itmust be substantially continuous and it must be of such thickness andstrength that it can withstand any abrasion thereof caused by thevarious other components of a shot shell as they are inserted thereinduring loading. The aluminum oxide coating on the inner wall 3 of thecase 1 can be applied by conventional chemical methods but is preferablyapplied by an anodic treatment and must exceed the thickness of theoxide coating produced by oxidation of aluminum in the air. Best resultshave been obtained with an anodically produced oxide coating of fromabout 10 microns to about 20 microns thickness on the inner wall of thecase. Likewise, the thickness of the other non-metallic adherent filmson the inner wall of the shot shell case or on the shot shouldpreferably be Within this range.

In older to clarify and to more fully describe the invention thefollowing is a description of embodiments thereof:

Conventional lead shot 4 is placed in an oblique tumbling barrel such asis conventionally used for cleaning shot and a solution of about 10parts Socony Vacuum #2300 microcrystalline Wax marketed-by the SoconyVacuum Oil Co. of New York and about parts can brass shell case.

2,919,647 r. g r

bon tetrachloride is sprayed on the shot. The solution is applied to theshot by spraying a small amount thereon and then tumbling the shot awhile to permit the solvent to evaporate after which more solution isadded, the intermittent spraying and tumbling process being continueduntil a wax film of about to 20 microns thickness substantiallycompletely covers the shot. After solvent removal by tumbling tofacilitate evaporation thereof, the shot is ready to load in thealuminum shot shells.

In another embodiment of this invention, an aluminum shot shell case 1is immersed about 30 seconds in a solution of from about four to aboutfive ounces sodium hydroxide per gallon of water maintained at atemperature of about 180 F. After rinsing in water to substantiallycompletely remove any sodium hydroxide solution clinging thereto, theshell case is anodized about 30 minutes in a percent sulfuric acid-watersolution at a current density of 12 to 15 amperes per square foot. Thetemperature of the solution during the anodizing treatment is maintainedwithin the range of about 68 F. to about 74 F. Conventional anodizingequipment is used, although an anode is placed within the cartridge caseto insure the formation of a coating of at least about .001 inch thickon the inner wall 3 of the case 1. After rinsing in water to remove thesulfuric acid solution, the shell case is immersed about 30 minutes in asolution of about one-half ounce nickel acetate per gallon of water at atemperature of about 200 F. The shell case is then rinsed'to remove thenickel acetate solution therefrom and is air dried.

No definite explanation of why the problem solved by this invention wasencountered in the manufacture of shot shells and not in riflecartridges or why a nonmetallic coating interposed between the shot 4and the wall 3 of the shot shell case 1 of a loaded shot shell improvesthe performance thereof is apparent at this time. metallic barrierprevents seizure between the shot and the inner Wall of the shot shellcase. 'In a shot shell, the shot charge 4 consisting of many smallspherical pellets can be considered to be essentially a fluid bodyexerting pressure in all directions when the shell is fired. Thus, thereis a tendency for the shot 4 to move radially against the shell wall 3and consequently, movement of the shot out of the shell case isretarded. It is believed the pressures exerted by the shot 4- radiallyagainst the shell case wall 3 increases the resistance of the shotcharge against forward motion and that this resistance is responsiblefor the high pressures obtained when an aluminum shot shell not havingthe barrier provided by this invention is fired. The non-metalliccoating is believed to reduce the friction between the shot and theshell case wall making it possible to propel the shot at the desiredvelocity with the development of less pressure. In a rifle cartridge,the projectile is a single body and does not exert a great radialpressure against the cartridge case. Tests have consistently shown adistinct improvement'in shot shells of all gauges provided by thisinvention over shot shells having an aluminum case not separated fromthe shot by a nonmetallic coating. As an example, 410 gauge shells madein accordance with this invention and loaded to have a velocity of about1000 feet per second at a distance of about 25 yards from the muzzle ofthe gun using a conventional shot shell powder 6, developed a pressureof from about 2000 to 3000 pounds per square inch less than did similarbut untreated aluminum shot shells.

The aluminum shot shell provided by this invention will functionproperly in inclement weather and it has been found that the case can bemanufactured at a cost which will not require the consumer to reload thecase. Although the price per pound of aluminum at the-present time issubstantially equal to that of brass, the "finished shot shell casecosts only about one-third the cost of a This lower cost is primarilydue tothe lighter weight 'of the aluminum but is also partially due Ithas been theorized, however, that the nonto the fact that aluminum shotshell cases can be more easily formed by extrusion processes than canshell cases be formed from brass. Furthermore, the shot patternsobtained with the aluminum shot shell provided by this invention aresubstantially equal to those of the paper shot shells because neitherthe non-metallic coating on the shot or the case interferes with theproper shot dispersion during the flight of the shot.

While this invention has been described in detail in the foregoing,variations or modifications within the skill of the art can be madetherein without departing from the spirit and scope of the invention.The 410 gauge shot shell has been used herein as an example but theinvention is applicable to other gauges including 12, 16 and 20 gaugeshot shells. i

Having thus described the invention what is claimed and is desired tosecure by Letters Patent is:

1. A shot shell comprising an aluminum case having a hollow defined byan inner surface of said case and containing a powder charge and aplurality of metallic shot pellets each having an exterior surface andexerting a radial pressure against the surface of the hollow duringfiring, and means to reduce the pressure developed by the powder chargeduring firing, said means comprising a non-metallic coating on one ofsaid surfaces and separa'ting said aluminum case and said shot pellets.

2. A shot shell comprising an aluminum case having a hollow defined byan inner surface of said case and containing a powder charge and aplurality of metallic shot pellets each having an exterior surface andexerting a radial pressure against the surface of the hollow duringfiring, and means to reduce the pressure developed by the powder chargeduring firing, said means comprising a non-metallic coating greater thanabout 10 microns thickness on one of said surfaces and separating saidaluminum case and said shot pellets thereby preventing seizure betweenthe metallic shot pellets and the aluminum shot she'll case.

3. A shot shell comprising an aluminum case having a hollow defined byan inner wall in said case and containing a powder charge and aplurality of metallic shot pellets exerting a radial pressure againstthe wall of the hollow during firing, and means to reduce the pressuredeveloped by said powder charge during firing, said means comprising anon-metallic coating greater than about 10 microns thickness on saidwall of the hollow of said aluminum case and separating said wall andsaid shot pellets thereby preventing seizure between the metallic shotpellets and the aluminum shot shell case.

4. A shot shell comprising an aluminum case having a hollow defined byan inner wall in said-case and containing a powder charge and aplurality of metallic shot pellets exerting a radial pressure againstthe wall of the hollow during firing, and means to reduce the pressuredeveloped by the powder charge during firing, said means comprising anon-metallic coating greater than about 10 microns thickness on saidmetallic shot pellets thereby separating said wall of thehollow in saidaluminum case and said shot pellets and preventing seizure between themetallic shot pellets and the aluminum shot shell case.

5. ,A shot shell having an aluminum case and metallic shot pellets anddisplaying substantially the same characteristics as a conventionalpaper shot shell of the same gauge and load of shot pellets whenprovided with the same powder charge as in said paper shot shell, saidshot she'll comprising an aluminum case having a hollow delined by aninner surface of said case, a plurality of metallic shot pellets withinthe hollow exerting aradial pressure against said inner surface duringfiring, each of said shot pellets having an exterior surface, means toadjust the pressure developed by the powder charge-and the velocity ofthe shot pellets to that commensurate with said paper shot shell, saidmeans comprising a non-metallic coating greater than about 10 micronsthickness on one of said surfaces and separating said aluminum .case

and said shot pellets thereby preventing seizure between the metallicshot pellets and the aluminum shot shell case.

is an aluminum oxide on said aluminum case.

References Cited in the file of this patent UNITED STATES PATENTSSpengler Feb. 6, 1940 FOREIGN PATENTS Great Britain of 1894 GreatBritain Oct. 27, 1936 Great Britain May 26, 1937 Great Britain Oct. 23,1940

1. A SHOT SHELL COMPRISING AN ALUMINUM CASE HAVING A HOLLOW DEFINED BYAN INNER SURFACE OF SAID CASE AND CONTAINING A POWDER CHARGE AND APLURALITY OF METALLIC SHOT PELLETS EACH HAVING AN EXTERIOR SURFACE ANDEXERTING A RADIAL PRESSURE AGAINST THE SURFACE OF THE HOLLOW DURINGFIRING, AND MEANS TO REDUCE THE PRESSURE DEVELOPED BY THE POWDER CHARGEDURING FIRING, SAID MEANS COMPRISING A NON-METALLIC COATING ON ONE OFSAID SURFACES AND SEPARATING SAID ALUMINUM CASE AND SAID SHOT PELLETS.